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June 30, 2003
Volume 81, Number 26
CENEAR 81 26 p. 27
ISSN 0009-2347

A FANTASTIC STINK
Giant flower's disgusting smell draws crowds--and chemists seeking to identify the odorants

ELIZABETH K. WILSON, C&EN WEST COAST NEWS BUREAU

Ted the Titan Slide Show
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PHOTOS COURTESY OF UNIVERSITY OF CALIFORNIA, DAVIS
R
emember the last time you left that liverwurst-and-Camembert sandwich sitting on the dash of your car for several days during a heat wave in Phoenix?

You would, if you had a chance to be present for the rare blooming of "Ted the Titan," a flower of the species Amorphophallus titanium (or titan arum) that's as famous for its odor of rotting meat as it is for its giant size.

Also known as the "corpse flower," the titan arum can extend nearly 9 feet high. It produces a bloom only once every few years that lasts only a day or so. Ted's home is the botanical conservatory at the University of California, Davis, although the species originally hails from Sumatra. Up to 1,000 people witnessed Ted's short-lived performance last week. The plant's remarkable perfume, emanating from a central spike, or spadix, is intoxicating to flies, which perform the job usually relegated to bees: pollination.

Ernesto Sandoval, the conservatory's curator, wafted his arms next to the 43-inch-high bloom--relatively diminutive, in titan arum terms--to enhance the olfactory experience.

"I've had two people gagging already today," he said cheerfully. As the bouquet--like rotten eggs laid by a decaying chicken in a clogged sewer pipe--drifted downwind, several more spectators followed suit with the gagging.

Ted was hooked up, like a hospital patient, to thermocouples, which measured the heat coming from the spadix. Scientists took impressions of the spadix, as well as tissue samples.

THE CHEMISTRY of Ted's smell isn't well characterized, although scientists have some strong suspicions. UC Davis plant biology professor Terence M. Murphy noted that tests on other Amorphophallus species revealed compounds that have a characteristic rotting-meat smell: dimethyl sulfides such as dimethyl disulfide and dimethyl trisulfide. Scientists also have detected in related plants amines with the appropriately evocative names of putrescine and cadaverine, also usually produced by rotting meat.

UC Davis entomology professor Bruce D. Hammock hopes to answer the question soon. Out of curiosity, he and his wife nosed by the conservatory during Ted's blooming. When they saw that nobody was doing any chemical analyses, he said, "on the spur of the moment, I ran around campus, dragged people out of their apartments, and by midnight we had a chemistry team."

Hammock, Murphy, and postdoc Katja Dettmer are running a battery of tests on air samples from the vicinity of the spadix, including a variety of chromatographic tests and mass spectrometry. They've also bubbled the gas through methane and hexane. They're still waiting for results, but "my nose as a chemist tells me [the compounds are] sulfur heterocyclic amines because it smells like three dead sheep," Hammock said.

Though the odor is obvious to humans, part of the difficulty in identifying its source, Dettmer explained, is that these compounds have very low odor thresholds, about 5 to 10 ppb. "The nose is a much better detector than detectors in the lab," she said.

A number of plants around the world have evolved this curious system of attracting flies with stink. As Sandoval explained, the flies zoom in on the odoriferous stalk, wandering around in a "euphoric, confused state" looking to deposit eggs. In doing so, they pick up pollen from the plant's male parts, depositing it on the female parts, fertilizing it.?

The titan arum sprouts as an ordinary-looking plant, with no hint of the show to come. Ted began as a seed planted in 1995, and then spent years building up enough energy in his underground stem to produce the blossom. "It's one of those plant strategies where it's approaching being an animal," said Timothy H. Metcalf, director of the conservatory.

Since Ted leads a sheltered life inside the conservatory, he'll either be fertilized by hand or, perhaps, with pollen from a fellow titan arum named Tiffy, which lives at California State University, Fullerton, and which bloomed three weeks previously.

Botanical gardens worldwide cultivate the titan arum. "Mr. Stinky" resides at the Fairchild Tropical Garden in Coral Gables, Fla.; "Tiny," at UC Santa Barbara.

Once scientists isolate the compounds that give Ted its distinctive stink, might there be any potential uses for them? "Maybe as fly attractants?" Murphy mused. "Something you put over in the corner of your backyard so the flies will leave your potato salad alone?"



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